1. Field of the Invention:
The present invention relates to slip rings for transferring signals from a rotating body to a non-rotating body. More specifically, the present invention relates to optical slip rings.
While the present invention is described herein with reference to an illustrative embodiment for a particular application, it is understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications and embodiments within the scope of the present invention.
2. Description of the Related Art:
Many applications require the transmission of electrical power or signals across rotary joints. Traditionally, this function has been accomplished with mechanical slip rings. Mechanical slip rings transfer electric current from a rotating body to a non-rotating body by means of brushes attached to one body which contact a conducting ring on the other body. Unfortunately, mechanical slip rings are subject to wear, generate electrical noise and are susceptible to electromagnetic interference such as that induced by nuclear explosion.
The recent advent of fiber optic technology has led to the creation of fiber optic slip rings which solve many of the problems associated with mechanical slip rings. In place of an electrical connection, fiber optic cables are used to transfer light energy between a rotating body and a non-rotating body. U.S. Pat. No. 4,109,997, issued to M. Iverson on Feb. 28, 1977 discloses a typical conventional fiber optic slip ring. The slip ring consists of two opposing faceplates, each containing bundles of fiber optic cables. The fiber optic cables have open ends which are formed into rings terminating on the supporting faceplates. Light energy projected from the open ends of the fiber optic cables mounted on one faceplate are received by the open ends of the optic fibers mounted on the opposing faceplate, even as the two faceplates rotate with respect to one another.
Unfortunately, the magnitude of the energy transferred faceplates will vary randomly as the faceplates rotate with respect to each other. As a result, the random arrangement of the fibers within the rings precludes an accurate prediction of the fluctuations in the magnitude of the energy transferred between the faceplates as a function of the relative position of the two bodies.
Accordingly, there is a need in the art for a lightweight optical fiber slip ring which affords a predictable correlation between the relative position of two counter-rotating bodies and the optical coupling therebetween.